U.S. patent application number 14/010971 was filed with the patent office on 2015-03-05 for battery pack leak detection assembly and method.
This patent application is currently assigned to Ford Global Technologies, LLC. The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to Xiaoguang Chang, Chuan He, Josephine S. Lee, Xu Wang.
Application Number | 20150063404 14/010971 |
Document ID | / |
Family ID | 52470682 |
Filed Date | 2015-03-05 |
United States Patent
Application |
20150063404 |
Kind Code |
A1 |
Chang; Xiaoguang ; et
al. |
March 5, 2015 |
BATTERY PACK LEAK DETECTION ASSEMBLY AND METHOD
Abstract
A method of detecting a leak in a battery pack according to an
exemplary aspect of the present disclosure includes, among other
things, calculating a predicted amount of thermal energy at a
position, measuring an actual amount of thermal energy at the
position, and comparing the predicted amount to the actual amount
to identify if a battery pack is leaking.
Inventors: |
Chang; Xiaoguang;
(Northville, MI) ; Wang; Xu; (Dearborn, MI)
; Lee; Josephine S.; (Novi, MI) ; He; Chuan;
(Northville, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Assignee: |
Ford Global Technologies,
LLC
Dearborn
MI
|
Family ID: |
52470682 |
Appl. No.: |
14/010971 |
Filed: |
August 27, 2013 |
Current U.S.
Class: |
374/4 |
Current CPC
Class: |
Y02E 60/10 20130101;
Y02T 10/70 20130101; B60L 58/24 20190201; H01M 10/6565 20150401;
H01M 10/486 20130101; G01M 3/002 20130101 |
Class at
Publication: |
374/4 |
International
Class: |
G01M 3/00 20060101
G01M003/00 |
Claims
1. A method of detecting a leak in a battery pack, comprising:
calculating a predicted amount of thermal energy at a position;
measuring an actual amount of thermal energy at the position; and
comparing the predicted amount to the actual amount to identify if
a battery pack is leaking.
2. The method of claim 1, further comprising moving a fluid through
the battery pack using a fluid movement device, the fluid entering
the battery pack at an inlet and exiting the battery pack at an
outlet, the fluid movement device positioned downstream from the
inlet and upstream from the outlet relative to a direction of flow
through the battery pack.
3. The method of claim 2, wherein the leaking comprises movement of
fluid to the battery pack through areas other than the inlet,
movement of fluid from the battery pack through areas other than
the outlet, or both.
4. The method of claim 2, wherein the fluid movement device is a
fan.
5. The method of claim 2, further comprising measuring an thermal
energy of fluid entering through the inlet to provide an inlet
fluid amount of thermal energy, comparing the inlet fluid amount to
the predicted amount to identify a location of the leaking.
6. The method of claim 4, calculating that the leak is between the
inlet and the fluid movement device if the inlet fluid amount of
thermal energy is greater than the actual amount of thermal energy
at the position.
7. The method of claim 1, wherein the position is at a battery cell
of the battery pack.
8. The method of claim 1, wherein the position is within the
battery pack.
9. The method of claim 1, including identifying a leak when the
actual amount is greater than the predicted amount by at least an
established threshold value
10. The method of claim 1, including identifying a leak when the
predicted amount is greater than the actual amount by at least an
established threshold value.
11. The method of claim 1, including measuring the actual amount of
thermal energy using a sensor positioned at or adjacent to battery
cell of the battery pack.
12. A leak detection assembly for a battery pack, comprising: a
sensor to determine an actual amount of thermal energy at an
position; and a controller to calculate a predicted amount of
thermal energy at the position, and to indicate that a battery pack
includes a leak based on a comparison of the predicted amount to
the actual amount.
13. The leak detection assembly of claim 12, comprising a fluid
movement device to move fluid from an inlet of the battery pack to
an outlet of the battery pack.
14. The leak detection assembly of claim 13, wherein the fluid
movement device comprises a fan.
15. The leak detection assembly of claim 13, wherein the leak
comprises movement of fluid to the battery pack through areas other
than the inlet, movement of fluid from the battery pack through
areas other than the outlet, or both.
16. The leak detection assembly of claim 13, including an inlet
sensor to measure an amount of thermal energy in fluid entering the
battery pack through the inlet, wherein the controller is
configured to compare the inlet fluid amount to the predicted
amount to identify a location of the leaking.
17. The leak detection assembly of claim 12, wherein the controller
indicates a leak when the predicted amount is greater than the
actual amount by at least an established threshold value.
18. The leak detection assembly of claim 12, wherein the controller
indicates a leak when the actual amount is greater than the
predicted amount by at least an established threshold value.
19. The leak detection assembly of claim 12, wherein the position
is within the battery pack.
20. The leak detection assembly of claim 12, wherein the position
is at or adjacent to a battery cell of the battery pack.
Description
BACKGROUND
[0001] This disclosure relates generally to a battery pack for an
electric vehicle and, more particularly, to detecting undesirable
thermal energy leaks and undesirable fluid leaks in the battery
pack.
[0002] Generally, electric vehicles differ from conventional motor
vehicles because electric vehicles are selectively driven using one
or more battery-powered electric machines. Conventional motor
vehicles, by contrast, rely exclusively on an internal combustion
engine to drive the vehicle. Electric vehicles may use electric
machines instead of, or in addition to, the internal combustion
engine.
[0003] Example electric vehicles include hybrid electric vehicles
(HEVs), plug-in hybrid electric vehicles (PHEVs), and battery
electric vehicles (BEVs). Electric vehicles are typically equipped
with a battery pack containing battery cells that store electrical
power for powering the electric machine. The batteries may be
charged prior to use, and recharged during drive by a regeneration
brake or engine.
[0004] Extended exposure to significant thermal energy levels can
shorten the useful life of a battery pack. Typically, the battery
pack is thus thermally insulated from the surrounding environment.
Further, a fan is used to move air through the battery pack. The
moving air regulates thermal energy levels. The fan typically draws
climate controlled air into the battery pack from a cabin of the
vehicle. This air moves through the battery pack and exits to the
cabin, the exterior of the vehicle, or trunk, etc. or combined of
them.
[0005] A leak in the battery pack permits undesirable levels of
fluid, thermal energy or both to communicate between an interior
and an exterior of the battery pack. Insulation breakage during
battery pack installation, customized vehicle work, etc. can cause
leaks in the battery pack. Leaks lead to increased operating time
for the fan, increased vehicle cabin temperatures, increased
battery temperatures, reduced vehicle performance, etc. Technicians
can undesirably devote considerable time to diagnosing and locating
leaks.
SUMMARY
[0006] A method of detecting a leak in a battery pack according to
an exemplary aspect of the present disclosure includes, among other
things, calculating a predicted amount of thermal energy at a
position, measuring an actual amount of thermal energy at the
position, and comparing the predicted amount to the actual amount
to identify if a battery pack is leaking.
[0007] In a further non-limiting embodiment of the foregoing method
of detecting a leak in a battery pack, the method includes moving a
fluid through the battery pack using a fluid movement device. The
fluid enters the battery pack at an inlet and exits the battery
pack at an outlet. The fluid movement device is positioned
downstream from the inlet and upstream from the outlet relative to
a direction of flow through the battery pack.
[0008] In a further non-limiting embodiment of any of the foregoing
methods of detecting a leak in a battery pack, the leaking
comprises movement of fluid to the battery pack through areas other
than the inlet, movement of fluid from the battery pack through
areas other than the outlet, or both. The leak, in some examples,
is a thermal leak through the insulation layer. Fluid may or may
not move through the leak.
[0009] In a further non-limiting embodiment of any of the foregoing
methods of detecting a leak in a battery pack, the fluid movement
device is a fan.
[0010] In a further non-limiting embodiment of any of the foregoing
methods of detecting a leak in a battery pack, the method comprises
measuring thermal energy of fluid entering through the inlet to
provide an inlet fluid amount of thermal energy, and comparing the
inlet fluid amount to the predicted amount to identify a location
of the leaking.
[0011] In a further non-limiting embodiment of any of the foregoing
methods of detecting a leak in a battery pack, the method includes
calculating that the leak is between the inlet and the fluid
movement device if the inlet fluid amount of thermal energy is
greater than the actual amount of thermal energy at the
position.
[0012] In a further non-limiting embodiment of any of the foregoing
methods of detecting a leak in a battery pack, the position is at a
battery cell of the battery pack.
[0013] In a further non-limiting embodiment of any of the foregoing
methods of detecting a leak in a battery pack, the position is
within the battery pack.
[0014] In a further non-limiting embodiment of any of the foregoing
methods of detecting a leak in a battery pack, the method includes
identifying a leak when the actual amount is greater than the
predicted amount by at least an established threshold value, for
example, three degrees Celsius.
[0015] In a further non-limiting embodiment of any of the foregoing
methods of detecting a leak in a battery pack, the method includes
identifying a leak when the predicted amount is greater than the
actual amount by at least an established threshold value, for
example, three degrees Celsius.
[0016] In a further non-limiting embodiment of any of the foregoing
methods of detecting a leak in a battery pack, the method includes
measuring the actual amount of thermal energy using a sensor
positioned at or adjacent to battery cell of the battery pack.
[0017] A leak detection assembly for a battery pack according to an
exemplary aspect of the present invention includes, among other
things, a sensor to determine an actual amount of thermal energy at
an position, and a controller to calculate a predicted amount of
thermal energy at the position, and to indicate that a battery pack
includes a leak based on a comparison of the predicted amount to
the actual amount.
[0018] In a further non-limiting embodiment of the foregoing leak
detection assembly, the assembly includes a fluid movement device
to move fluid from an inlet of the battery pack to an outlet of the
battery pack.
[0019] In a further non-limiting embodiment of any of the foregoing
leak detection assemblies, the fluid movement device comprises a
fan.
[0020] In a further non-limiting embodiment of any of the foregoing
leak detection assemblies, the leak comprises movement of fluid to
the battery pack through areas other than the inlet, movement of
fluid from the battery pack through areas other than the outlet, or
both. The leak may also comprise a thermal leak or movement of
thermal energy (and no fluid) from the battery pack through the
leak.
[0021] In a further non-limiting embodiment of any of the foregoing
leak detection assemblies, the assembly includes an inlet sensor to
measure an amount of thermal energy in fluid entering the battery
pack through the inlet, wherein the controller is configured to
compare the inlet fluid amount to the predicted amount to identify
a location of the leaking.
[0022] In a further non-limiting embodiment of any of the foregoing
leak detection assemblies, the controller indicates a leak when the
predicted amount is greater than the actual amount by at least an
established threshold value, for example, three degrees
Celsius.
[0023] In a further non-limiting embodiment of any of the foregoing
leak detection assemblies, the controller indicates a leak when the
actual amount is greater than the predicted amount by at least an
established threshold value, for example, three degrees
Celsius.
[0024] In a further non-limiting embodiment of any of the foregoing
leak detection assemblies, the position is within the battery
pack.
[0025] In a further non-limiting embodiment of any of the foregoing
leak detection assemblies, the position is at or adjacent to a
battery cell of the battery pack.
DESCRIPTION OF THE FIGURES
[0026] The various features and advantages of the disclosed
examples will become apparent to those skilled in the art from the
detailed description. The figures that accompany the detailed
description can be briefly described as follows:
[0027] FIG. 1 illustrates a schematic view of an example electric
vehicle powertrain.
[0028] FIG. 2 illustrates a schematic view of an example battery
pack used within the electric vehicle powertrain of FIG. 1.
[0029] FIG. 3 illustrates the flow of an example method used to
identify leaks within the battery pack of FIG. 2.
DETAILED DESCRIPTION
[0030] FIG. 1 schematically illustrates a powertrain 10 for an
electric vehicle. Although depicted as a hybrid electric vehicle
(HEV), it should be understood that the concepts described herein
are not limited to HEVs and could extend to other electrified
vehicles, including but not limited to, plug-in hybrid electric
vehicles (PHEVs) and battery electric vehicles (BEVs).
[0031] In one embodiment, the powertrain 10 is a powersplit
powertrain system that employs a first drive system and a second
drive system. The first drive system includes a combination of an
engine 14 and a generator 18 (i.e., a first electric machine). The
second drive system includes at least a motor 22 (i.e., a second
electric machine), the generator 18, and a battery pack 24. In this
example, the second drive system is considered an electric drive
system of the powertrain 10. The first and second drive systems
generate torque to drive one or more sets of vehicle drive wheels
32 of the electric vehicle.
[0032] The engine 14, which is an internal combustion engine in
this example, and the generator 18 may be connected through a power
transfer unit 36, such as a planetary gear set. Of course, other
types of power transfer units, including other gear sets and
transmissions, may be used to connect the engine 14 to the
generator 18. In one non-limiting embodiment, the power transfer
unit 36 is a planetary gear set that includes a ring gear 40, a sun
gear 44, and a carrier assembly 48.
[0033] The generator 18 may be driven by engine 14 through the
power transfer unit 36 to convert kinetic energy to electrical
energy. The generator 18 can alternatively function as a motor to
convert electrical energy into kinetic energy, thereby outputting
torque to a shaft 52 connected to the power transfer unit 36.
Because the generator 18 is operatively connected to the engine 14,
the speed of the engine 14 can be controlled by the generator
18.
[0034] The ring gear 40 of the power transfer unit 36 may be
connected to a shaft 56, which is connected to vehicle drive wheels
32 through a second power transfer unit 60. The second power
transfer unit 60 may include a gear set having a plurality of gears
64. Other power transfer units may also be suitable. The gears 64
transfer torque from the engine 14 to a differential 68 to
ultimately provide traction to the vehicle drive wheels 32. The
differential 68 may include a plurality of gears that enable the
transfer of torque to the vehicle drive wheels 32. The second power
transfer unit 60 is mechanically coupled to an axle 72 through the
differential 68 to distribute torque to the vehicle drive wheels
32.
[0035] The motor 22 (i.e., the second electric machine) can also be
employed to drive the vehicle drive wheels 32 by outputting torque
to a shaft 78 that is also connected to the second power transfer
unit 60. In one embodiment, the motor 22 and the generator 18
cooperate as part of a regenerative braking system in which both
the motor 22 and the generator 18 can be employed as motors to
output torque. For example, the motor 22 and the generator 18 can
each output electrical power the battery pack 24 through a high
voltage bus 82.
[0036] The battery pack 24 may be a high voltage battery that is
capable of outputting electrical power to operate the motor 22 and
the generator 18. Other types of energy storage devices and/or
output devices can also be used with the electric vehicle.
[0037] Referring now to FIG. 2, the example battery pack 24
includes a plurality of individual battery cells 86 and a fan 90. A
battery pack housing 94 holds the battery cells 86 and the fan 90.
The battery pack housing 94 includes an insulative layer 96 to
thermally insulate the battery pack 24. The battery pack housing 94
can include other layers in addition to the insulative layer
96.
[0038] The battery pack 24 includes a flowpath F extending from an
inlet 98 to an outlet 102. The battery cells 86 are positioned
within the flowpath F. The fan 90 moves a fluid along the flowpath
F from the inlet 98 to the outlet 102. The fluid, in this example,
is drawn from a passenger cabin 110 of the vehicle. The fluid moves
from the outlet 102 back to the passenger cabin 110.
[0039] In another example, the fluid moves from the outlet 102 to
an area outside of the passenger cabin 110, such as through an
outlet 102'. The fluid may move through the outlet 102' instead of,
or in addition to, moving through the outlet 102.
[0040] The fan 90 is a type of fluid movement device. A fan motor
104 drives a shaft 108 that extends through the battery pack
housing 94 to drive the fan 90. The fan 90 is downstream from the
inlet 98 and upstream from the outlet 102 relative to a general
direction of flow along the flowpath F.
[0041] Some of the battery cells 86u are positioned upstream from
the fan 90 relative to a general direction of flow through the
battery pack 24. Other battery cells 86d are positioned downstream
from the fan 90 relative to the general direction of flow through
the battery pack 24.
[0042] Fluid moving along the flowpath moves across the battery
cells 86, which regulates the amounts of thermal energy in the
battery cells 86. In one example, fluid moves across the battery
cells 86 to carry thermal energy away from the battery cells 86 and
thereby lower a temperature of the battery cells 86.
[0043] A plurality of thermal energy sensors 118 extend into the
battery pack 24. The sensors 118 collect thermal energy
measurements from the battery pack 24. The temperatures of the
battery cells 86 within the battery pack 24 can range, for example,
from -40 to 65 degrees Celsius, so the example thermal energy
sensors 118 are able to collect thermal energy measurements across
at least this range.
[0044] In this example, some of the sensors 118b measure thermal
energy amounts at ten separate locations that are within or near
the groups of battery cells 86. Five of the sensors 118b measure
thermal energy at locations within the battery cells 86u that are
upstream from the fan 90. Five of the sensors 118b measure thermal
energy amounts at locations within the battery cells 86d that are
downstream from the fan 90.
[0045] The readings from the sensors 118b reveal an actual amount
of thermal energy at the locations. When the location is on (or
sufficiently close to) one or more of the battery cells 86, the
readings from the sensors 118b represent an actual amount of
thermal energy in those battery cells 86.
[0046] Another of the sensors 118i measures an amount of thermal
energy in the flow moving through the inlet 98.
[0047] The sensors 118 are operably coupled to a controller 122
that collects the thermal energy readings from the sensors 118.
[0048] Leaks can develop in the battery pack housing 94. Leaks
permit undesirable fluids, thermal energy, or both to move to or
from the battery pack housing 94 at a location other than the inlet
98 and the outlet 102.
[0049] The example battery pack 24 includes upstream leaks L.sub.u
that are upstream relative to the fan 90. The upstream leaks
L.sub.u permit fluid or thermal energy outside the passenger cabin
110 to be drawn into the battery pack 24, rather than fluid from
the passenger cabin 110.
[0050] The example battery pack 24 includes downstream leaks
L.sub.d that are downstream relative to the fan 90. The downstream
leaks L.sub.d permit fluid or thermal energy within the battery
pack 24 to escape from the battery pack 24 though a location other
than the outlet 102.
[0051] The upstream leaks L.sub.u offer little resistance to fluid
moving into the battery pack 24 compared to the relatively
restricted flow from the passenger cabin 110. The upstream leaks
L.sub.u can cause an amount of thermal energy in the battery cells
86 to increase or decrease depending on the ambient temperature of
the battery pack 24 and the temperature of the fluid in the
environment that enters the battery pack 24 via the upstream leaks
L.sub.u Fluid entering the battery pack 24 via the upstream leaks
L.sub.u has not been conditioned within the passenger cabin
110.
[0052] In hot weather, for example, fluid moving into the battery
pack 24 through the upstream leaks L.sub.u could be very hot, which
could cause some areas of the battery pack 24 near the upstream
leaks L.sub.u to heat up disproportionately to other areas. In cold
weather, fluid moving into the battery pack 24 through the upstream
leaks L.sub.u could be very cold and cause some areas of the
battery pack 24 near the downstream leaks L.sub.d to cool
disproportionately to other areas.
[0053] In an example embodiment of this disclosure, the controller
122 identifies that the battery pack 24 has leaks using, in part,
readings from the sensors 118b, the sensor 118i, or both. If the
controller 122 calculates that the battery pack 24 includes leaks,
a technician can then inspect and repair the battery pack 24. If a
leak is found, the leak can be repaired to ensure that flow across
the battery cells 86 is not influenced by the leak.
[0054] Referring now to FIG. 3 with continuing reference to FIG. 2,
to detect leaks, an example method 200, at a step 210, calculates a
predicted amount of thermal energy at a position within the battery
pack 24. The method 200 also measures, at a step 220, the actual
amount of thermal energy at the position. The method 200 may use,
for example, readings of thermal energy from the sensors 118b to
measure the actual amount of thermal energy at the position.
[0055] At a step 230, the method 200 compares the predicted amount
of thermal energy to the actual amount of thermal energy. The
method 200 detects leaks in the battery pack 24 based on this
comparison.
[0056] The method 200 may rely, in part, on a battery pack
temperature estimation equation, which has been reproduced below as
equation (1).
t [ C p , cell T cell ] + t [ E cell ( SOC ) ] = h ( T air - T cell
) + V cell I Equation ( 1 ) ##EQU00001##
[0057] In this example, C.sub.p, cell represents the heat capacity
of the battery cell 86 and harnesses associated with the battery
cell 86. E.sub.cell represents the electrical energy in the battery
cell 86. T.sub.air represents a temperature of the air into the
battery pack 118i, T.sub.cell represents a temperature of a battery
cell 86, and h represents the heat transfer coefficient. V.sub.cell
represents the terminal voltage of the cell 86. I represents the
pack current. In the current sign convention, a positive value is
for a charge current. Thus, equation (1), in this example, sets the
thermal and electrical energy increase in the battery pack 24 to be
equal to both the heat transfer into battery pack 24 and the power
generated by the battery pack 24.
[0058] To calculate the estimated temperature at a position within
the battery pack 24, such as a selected battery cell 86, the method
200 may determine heat transfer out (HT.sub.out) of battery cell 86
using equation (2), which has been reproduced below:
HT.sub.out=(h.sub.0+fan_air_flow_rate.times.h.sub.fan.sub.--.sub.on).tim-
es.(T.sub.air-T.sub.cell) Equation (2)
[0059] The heat transfer coefficient h.sub.0 and the fan on heat
transfer coefficient h.sub.fan.sub.--.sub.on are constants and can
be obtained with fan off and fan on battery pack temperature test
data. A person having skill in this art and the benefit of this
disclosure would be able to obtain these coefficients.
[0060] The heat generated by the battery cell is, essentially, the
electrical energy consumed. The heat generated by the battery cell
is represented by BP.sub.HG and can be calculated using equation
(3), which has been reproduced below:
BP.sub.HG=I.sup.2.times.R.sub.cell Equation (3)
[0061] In Equation (3), I is the electrical current through the
battery pack 24 and R.sub.cell is the total electrical resistance
(both cell and harnesses) of the battery cell 86.
[0062] The battery cell temperature T.sub.cell can then be
estimated using Equation (4), which has been reproduced below:
BP.sub.HG-HT.sub.out=C.sub.p,cell.times.(d(T.sub.cell)/dt) Equation
(4)
[0063] Solving the above equations provides T.sub.cell, which is an
estimate of the thermal energy in the battery cell 86 associated
with the position. To compensate the delay of sensor measured
temperature, filter(s) and/or pure delay can be used to simulate
the real sensor reading. In the example method, if temperature of
the battery cell 86 (measured by one or more of the sensors 118b)
is significantly different than estimated temperature of the
battery cell T.sub.cell, the battery pack 24 is considered to have
a leak.
[0064] In some examples, the predicted amount of thermal energy and
the actual amount of thermal energy are represented as temperatures
measured in degrees Celsius. If the predicted amount equals or
exceeds an established threshold value, the method 200 indicates
that the battery pack 24 is leaking. For example, if the
established threshold value is an absolute value of three degrees
Celsius, and the predicted amount is three or more degrees Celsius
greater than the measured amount, the method 200 indicates that the
battery pack 24 is leaking. In addition, if the predicted amount is
three or more degrees Celsius less than the actual amount of
thermal energy, the method 200 indicates that the battery pack 24
is not leaking. In this example, the threshold value is
calibratable and can be adjusted based on specific requirements,
such as battery pack 24 size.
[0065] In one example, the battery pack 24 is only to be considered
leaking if, in addition to the predicted amount varying three or
more degrees from the actual amount, a fault associated with the
sensor 118b has not also been detected within a certain timeframe,
say this drive cycle. An example fault is a sensor 118b that has
failed and does not provide a reading, for example.
[0066] A further example embodiment of this disclosure can
determine the general positions of leaks within the battery pack 24
to assist the technician inspecting the battery pack 24. For
example, in hot weather, the air outside the battery pack 24 is
relatively hot, and the thermal energy levels of the battery cells
86 upstream from the leak will be higher than those downstream from
the leak. The controller 122 calculates the location within the
battery pack 24 where the temperature transitions from a lower to a
higher temperature. This location is then flagged as the likely
location of the leak.
[0067] The technician begins a search for the leak in the flagged
location, which can help reduce inspection time. The controller 122
uses information collected by the sensors 118b, the sensor 118i, or
both to calculate the location of the temperature transition.
[0068] Identifying the general location of the leak could involve
calculating whether the leak is on, for example, the driver or
passenger side of the battery pack 24. Identifying the general
location of the leak could be more specific, such as a specific
battery cell 86 that is closest to the leak.
[0069] The controller 122 can identify that the leak is an upstream
leak L.sub.u, in one example, when the temperature of fluid moving
out of the outlet 102 into the passenger cabin 110 is elevated.
This may be due to the flow from the passenger cabin 110 mixing
with the hotter fluid entering the flowpath F through the upstream
leak L.sub.u The fluid moving out of the outlet will cause the
temperature measured by the inlet sensor 118i to be higher than the
temperature measured by the sensors 118b upstream from the upstream
leak L.sub.u.
[0070] In one example, the controller 122 can identify that the
leak is a downstream leak L.sub.d. Fluid can move out of the
battery pack 24 through the downstream leak L.sub.d instead of
through the outlet 102. The fluid moves through the path of the
downstream leak L.sub.d rather than through the outlet 102 due to
less air resistance along the path provided by the downstream leak
L.sub.d versus the resistance associated with the outlet 102. The
resistance of the outlet 102 is typically higher than the
resistance at the location of the leak due to a pipe 130 and the
structure of the outlet 102 providing a relatively open path to the
passenger cabin 110.
[0071] The controller 122 calculates an area having the leak
recognizing that areas of the battery pack 24 downstream from the
leak will have elevated temperatures relative to areas of the
battery pack 24 upstream from the leak. The relative elevated
temperatures are due to less air movement across the areas
downstream from the leak.
[0072] In some examples, if the battery pack 24 includes leaks both
upstream and downstream from the fan 90, fluid moving through the
leak paths will be cycled out of the battery pack 24. The battery
pack 24 will then use flow from the area around the pack instead of
passenger cabin 110 and the battery pack 24 will be heated very
quickly. Fan speed will have little impact on the ability of the
fan 90 to reduce the temperature of the battery cells 86 within the
battery pack 24.
[0073] Although the different non-limiting embodiments are
illustrated as having specific components or steps, the embodiments
of this disclosure are not limited to those particular
combinations. It is possible to use some of the components or
features from any of the non-limiting embodiments in combination
with features or components from any of the other non-limiting
embodiments. Further, unless otherwise specified, the steps may be
performed in any order.
[0074] The preceding description is exemplary rather than limiting
in nature. Variations and modifications to the disclosed examples
may become apparent to those skilled in the art that do not
necessarily depart from the essence of this disclosure. Thus, the
scope of legal protection given to this disclosure can only be
determined by studying the following claims.
* * * * *